
/**
 * stringToBytes_UTF8
 * contributed by elhigu
 */
export function stringToBytes_UTF8(s: string): number[] {
  // http://stackoverflow.com/questions/18729405/how-to-convert-utf8-string-to-byte-array
  function toUTF8Array(str: string): number[] {
    var utf8: number[] = [];
    for (var i = 0; i < str.length; i++) {
      var charcode = str.charCodeAt(i);
      if (charcode < 0x80) utf8.push(charcode);
      else if (charcode < 0x800) {
        utf8.push(0xc0 | (charcode >> 6),
          0x80 | (charcode & 0x3f));
      }
      else if (charcode < 0xd800 || charcode >= 0xe000) {
        utf8.push(0xe0 | (charcode >> 12),
          0x80 | ((charcode >> 6) & 0x3f),
          0x80 | (charcode & 0x3f));
      }
      // surrogate pair
      else {
        i++;
        // UTF-16 encodes 0x10000-0x10FFFF by
        // subtracting 0x10000 and splitting the
        // 20 bits of 0x0-0xFFFFF into two halves
        charcode = 0x10000 + (((charcode & 0x3ff) << 10)
          | (str.charCodeAt(i) & 0x3ff));
        utf8.push(0xf0 | (charcode >> 18),
          0x80 | ((charcode >> 12) & 0x3f),
          0x80 | ((charcode >> 6) & 0x3f),
          0x80 | (charcode & 0x3f));
      }
    }
    return utf8;
  }
  return toUTF8Array(s);
};
